The horrors of 9/11 were revisited Friday when landing gear from a hijacked plane was discovered hidden behind the controversial “Ground Zero Mosque.”

A part of a landing gear, apparently from one of the commercial airliners destroyed on September 11, 2001, has been discovered jammed between the rear of 51 Park Place and the rear of the building behind it, 50 Murray Street. DCPI

The grim discovery by surveyors bolstered claims the city mismanaged the cleanup after the terrorist attack, which has left more than 1,100 victims still unaccounted for, nearly 12 years later.

The torn relic also brought renewed heartache to some victims’ families who opposed plans to build a Muslim place of worship at 51 Park Place, just two blocks north of the 9/11 Memorial.

“The main goal was build, build, money, money, money, the hell with human remains, and this is what we have today,” said Sally Regenhard, who lost her firefighter son on 9/11. “Some people say, ‘I’m shocked.’ I’m not shocked.”

Regenhard said the location of the find felt like a “double-edged sword” for those who called for the area to be landmarked.

“This is a legacy of failure and disregard. Perhaps finding the fuselage now is finally going to make people realize this.”

The NYPD is securing the location as it would a crime scene, documenting it photographically and restricting access until the Office of the Chief Medical Examiner completes its health and safety evaluation. DCPI

The discovery was made in a narrow stretch behind the building, resurrecting memories of the bright September morning when two planes slammed into the twin towers.

“When I heard the news, right away I was like, ‘Oh!’ ” said Ilila Tahlov, 47, a hairdresser at Ray’s Barber Shop across from the building on Park Place. “It all came back,” she said, covering her face as if reliving the day.

On Friday, the area was taped off like a crime scene as word of the unlikely find spread.

“There was a lot of dirt and stuff in there,” a police source told the Daily News. “We didn’t know what it was.”

A member of the NYPD aviation unit went to the scene and confirmed it was a plane’s landing gear. A check of its serial number linked the wreckage to the attack that killed 2,753 [sic] people.

“It’s amazing,” said Van Vanable, 63, a former One World Trade Center ironworker. “I was part of the cleanup. It’s still devastating to think about — how people suffered from then to now.”

The gear remained untouched Friday and won’t be moved until officials can test it for contaminants, said Ellen Borakove, spokeswoman for the city medical examiner.

Before removing the item, investigators will search the surrounding area for any other artifacts linked to the 9/11 attacks.

It’s the same protocol used all along in the World Trade Center probe — similar to when debris was recovered from a manhole in 2006, she said.

“I don’t think anyone can get near there,” Borakove said.

The metal piece was discovered Wednesday by surveyors between two of the buildings owned by developer Sharif El-Gamal, sources said. They immediately called 911.

El-Gamal just purchased an adjacent property at 43 Park Place for $8 million.

Cops were investigating how the gear got there, including the possibility it was lowered into place because a piece of rope was found intertwined with the metal.